A spreadsheet records what someone typed. A line records what happened.
Excel is not a bad tool, and this is not an argument that it is. It is an argument about where the numbers in it come from, and about what you can and cannot demonstrate six months later.
A spreadsheet is enough when
- One or two machines are tracked, by people who stand next to them.
- The figure starts a conversation and is not expected to prove what happened.
- Stops are long enough that everyone writes them down.
Move OEE onto machine data when
- The morning starts with someone reconciling yesterday’s sheets.
- Short stops are a loss nobody has a figure for.
- Lines or sites need figures computed the same way, or a figure has to be shown to an auditor.
Keep the reports people already read: a pivot table can stay a pivot table, fed from machine data rather than by hand.
The same seven questions, asked of both.
Every row describes what each approach does, not which one wins. One row has the person filling in the sheet ahead, and it stays in.
| Spreadsheet | VZIAM | |
|---|---|---|
| Where the number comes from | Typed in by an operator or supervisor, from a reading or an estimate. | Read from the machine controller as the cycle happens. |
| When it is available | After the shift, once the sheet has been filled in and collected. | As the shift runs, on the line and in the office at the same time. |
| Which stops get recorded | The ones long enough to be worth the interruption, which excludes most of them by count. | All of them, with a reason asked only for the ones long or frequent enough to warrant it. |
| How OEE is defined | Per workbook. Each site’s formulas evolve separately, so two sites rarely compute it the same way. | Once, in the engine, to AFNOR NF E60-182: the same definition on every line and every site. |
| What can be checked afterwards | The current state of the file. Earlier versions exist only if somebody saved them. | The categorised time series the figure was computed from, retained and queryable. |
| Who can see it | Whoever has the file, in the version they were sent. | Anyone with access, looking at one record rather than a copy of it. |
| What a person still does better | Recognising that a jam is the third of its kind this week and that the guide rail is worn. | Nothing here replaces that. It gives it somewhere to be recorded so it is not lost at the handover. |
| The reports you already like | Rebuilt by hand from the workbook, by whoever maintains it. | If the weekly view your team reads is a pivot table, it can stay one, fed by the API rather than by hand. Replacing a data source is a smaller and much more survivable change than replacing everybody’s reports on the same morning. |
The spreadsheet has no licence fee and is not free.
The cost of a spreadsheet-based OEE is paid in four places, none of which appear on an invoice.
Somebody’s morning
A supervisor reconciles yesterday’s sheets before the production meeting can start, chasing missing entries, correcting obvious typos, rebuilding the chart. That hour is spent every day and is invisible in every budget.
The losses nobody enters
A stop has to be noticed, judged worth recording, and typed in. Short stops fail all three tests, so they are absent from the data, and a loss that is absent from the data is never worked on.
Times remembered rather than read
A stop noted at the end of a shift is placed to the nearest five or ten minutes, from memory, by someone who was busy at the time. The reason is usually right. The duration is an estimate, and every estimate rounds towards the tidier number.
Nothing to show an auditor
A workbook has no record of who changed which cell, or when. That is not a criticism of Excel, which was never built to be an evidence store; it is a problem when the workbook is the only account of what the plant produced.
The other comparisons.
Plan the change before it reaches the line.
Request a demo and an engineer looks at how your production runs today, shows how the software would fit around it, and where a pilot on one line would start.
01Pick a time
Choose a slot in the calendar, and note what you make and what reads your machines today.
02Screen shared with an engineer
A video call with someone who builds the software, in English or French.
03What would connect
For each machine, its path: native (OPC UA, MQTT or HTTP push), through a gateway, or nothing to build.